Marine propulsion plant



Oct. lO, 1950 F. RoEscH MARINE PRoPULsIoN PLANT Filled 4April 25, 1944 3sheets-sheet 1 lNvEN'roR fab/rz ESCH.

BY www ATTORNEY Oct, 10, 1950 y F, RoEsCH Y 2,525,460 v MARINEPRoPUmsIoN PLANT BY /fw ATTORNEY F. ROESCH MARINE PROPULSION PLANT ocr.10,1950

3 Sheets-Sheet 3 Filed April l25, 1944 INVENTORA P/rz /QEJc/A ATTO R NEY Patented Oct. 10, 1950 UNITED STATES PATENT OFFICE MARINE PROPULsIoNPLANT y Fritzl Roesch, Lucerne, Switzerland Application April 25, 1944,Serial No. 532,663

The invention relates to a marine propulsion plant, its purpose'being tomake high propulsion powers possible in an economic way while at thesame time avoiding an excessive thermal or me-A chanical stressing ofthe internal combustion engines. y

The development of marine propulsion is leading to higher speeds andthus to higher powers. When ships are re-engined, however,A in spite ofthe higher power required, it is necessary that the previous engineweight should if possible not be exceeded, while in new Vessels lowweight and small dimensions of the engine are aprimary aim. This makespossible for the new engines, as opposed to the larger and' heavierlerr-Y gines employed hitherto, a much greater freedom in theinstallation of the plant in the vessel, so that space can be used whichis not very suitable for cargo; Even in high-powered plants, thearrangement of the -engine room amidships is no longer a necessity, sothat this space can now be employed as useful space.

The power of internal combustion engines can be increased not only by anincrease in the speed, but also by an increase of the mean effectivepressure pm.- The latter is obtained by increasing the quantity of fuelinjected into the combustion cylinder. The maximum quantity of fuel forfull power, however, is limited by a definite quantity of air, whichmust be greater than the quantity of air theoretically necessary forcombustion.

In modern marine engines an increase in the fuel quantity would bepossible only if the quantity of air customary up to date could be morecompletely utilized. This, however, would raise the temperatures in thecylinder and thus the thermal stressing of the engine. In order to keepthis stressing low, it is possible to increase the customary quantity ofair by supercharging. However, the greatest economic and thermaladvantages of supercharging fall onlywithincertain fixed limits. It isclear that a low supercharglng pressure corresponds to a low load on theengine and a high supercharging pressure to a high load.

In marine propulsion certain difliculties stand in the way of thelapplication of supercharging. These difculties lie in the fact that theacceleration of the ship by the main engine is limited in the followingway, At the moment when the load on the internal combustion engineshould be increased, the sup'ercharging pressure corresponds to theprevailing load .and not to the new Vload and the fuel supply iscustomarily set to the Amaximum quantity corresponding to theYprevailing supercharging pres- 8 Claims. (Cl. 1704-1375372) sure. Rapidacceleration of the engine and thus of the ship by increasing the fuelsupply alone is thus only possible at the cost of marked thermaloverloading of the engine. l

As the shafting, the propeller and the ship itself have to beaccelerated with the internal combustion engine until the superchargingpressure corresponds to the new load, the excessive thermal stress onthe engine in marine service is not only very high but also lasts aconsiderable time. Thus, on the one hand, such overstressing mustbefavoided at all costs for the sake of the reliability in service ofmarine plant, and the acceleration through an increase in the fuelsupply` alone can therefore only be small. On the other hand, goodmanuvrability and the at# tainment of high average speeds over the wholeof a voyage demand as high an acceleration as possible in marineservice.

In o-rder to fulfill the requirements both of reliability and of highacceleration, it is proposed in the present invention to provide one ormore two-strokeinterr1al combustion engines with a turbine driven bytheir exhaust gases landv a, supercharging' plant, which latter draws induring one vrevolution of the engine or engines a quantity of air whosevolume in its suction state is twice the swept volume of the combustioncylinder or more, but in its compressed state does not exceed twice theswept volume, the engine being coupled to a propeller with blades advjustable during service.

While the special type of supercharging makes possible the desiredincreases in power and/or decreases in weight but still remains withineconomic limits, the difficulty of low acceleration of the vessel isovercome in suchy a plant by the effect of an adjustment of thepropeller blades co-ordinated in time with the supercharging process.

The fact that the required normal speed of the vessel is reached morequickly offers f the advantage of a shortening of the ytotal time Fig. 2gives the comparison between the 3 tion and compressed air volume in thesupercharged plant and the swept Volume of the engine.

Figs. 3-6 show a device for successively effective regulation and somedetails.

Fig. 7 shows the relationship between ignition lag and power.

Figs. 8 and 10 illustrate two-stroke internal combustion engines withcombined regulating and blade adjusting devices for limiting the pres'-sure drop in dependence on the supercharging pressure.

Figs. 9,V l1 and 12 illustrate variations of details in Figs. 3, 8 and10.

The curves m, n in Fig. l show the fuel consumption b for various ratiosof the volume of air Va drawn in by the compressor-to the swept volumeVh of the combustion cylinder'. The curveY m shows that the fuelconsumption b in grams/B. H. P.hour of a normal non-superchargedtwo-stroke engine rapidly takes on, above the ratio Va/WL=1.6, valueswhich are no longer economically admissible.

The curve n applies for a supercharged twostroke internal combustionengine working accordingto the invention in which the fuel consumption bin grams/B. H. P.hour, in contrast to that in non-superchargedtwo-stroke engines, continues to decrease above the ratio Va/Vh=1.6. If,therefore, the limiting value of at least double the swept volume Vh ofthe combustion cylinder is used for the air volumeV Va drawnA in by thecompressor during one revolution of the crankshaft of the engine, thatis Va/VhZ, then the internal ccmbustionvengine will receive at al1loads, and in particular when starting, the quantity of air which isnecessary in order to make possible undisturbed service.

According to the curve O, Fig. 1, the fuel consumption b in grams/B. H.P.hour also changes when there is a change in the ratio of the volume ofair delivered by the compressor in its ,compressed stated Vv to theswept volume VIL. The fuel consumption b also memains within economiclimits when the volume of air Vv delivered during one revolution of thecrankshaft of the engine is such that in its compressed state it isequal to or less than twice the swept volume Vh of the combustioncylinder, while from the limiting value Va/Vh=2' onwards it begins toincrease rapidly and becomes uneconomical. An economic fuel consumptionis thus obtained when the two ratio limits are observed. Y

In order to give a clear representation of the relationship ofthe-volumes, Fig. 2 shows a section through a two-stroke internalcombustion engine with one compressor cylinder for each combustioncylinder. The supercharging plant of such a multicylinder engine thusincludes all the compressor cylinders K together, whose suction volumeVa=the number of cylinders the length of stroke the area of pistonsurface=e.HKa.D2K/41r, and thusI the swept volume Vh of the combustioncylinder=e.HB.Ds2/41r. The compressor piston AY draws the air throughthe suction valve C during the downward stroke, and compresses it duringthe compression stroke from theflower dead centre, the line a, until thepiston A has reached the line'v corresponding to the pressure in thesupercharging air container E. Then thedelivery valve F opens and.` theair is forced out into the container E. During the downward stroke ofthe combustionV piston L, the exhaust ports open into the exhaust I pipeM, to which an exhaust gas turbine is con- 4 nected. Thereuponscavenging and supercharg'd ing air flows out of the container Elthrough the admission ports into the combustion cylinder B. Since acompressor cylinder K is provided for each combustion cylinder B and thediameters of both are equal, DB=DK, the volumes to be compared can berepresented by the shaded rectangles. The strokes HK@ of the compressorpiston A, from the-lower tothe upper dead centre,

and HKV, from the line o up to the upper dead centre, and the stroke ofthe combustion piston B HB, provide a direct method of measuring thevolumes Va, Vo and WL. rIhen, for instance, HKa=v2.3HB and HKvzlHB.

The eight-cylinder two-stroke internal combustion engine I with opposedpistons in Fig. 3 has an exhaust-gas turbine 'l connected to the exhaustpipe 8, and theexhaust gases from this turbine pass to the Aatmospherethrough the pipe 9. The turbine I drives the compressor I8, formingtogether thefsupercharging plant. The compressor I8 is connected to thecombustion cylinders'k through the super charging pipe I2. Thecrankshaft of the engine I provides the compressor I8, through thereduction gear 2li and the overtakingk coupling 2 I, with asupplementary drive in case the power from the turbine 'l should be toosmall. The quantity of fuel to be injected is measured by means of thefuel pumps 26 and supplied to the combustion spaces of the cylinders ofengine I. y

The internal combustion .engine I drives the propeller 4, whose blades 5can be adjustedduring service. For the sake, of clarity,. only one ofthetwo, three or four blades is shown. l

In contrast to the customary method of control of variable pitchpropellers, the control in the present case is such that, when theoutput of the two-stroke Diesel `engine is increased a temporaryin-crease in the speed of the engine is obtained without any increase ofits torque, orof the fuel quantityinjected, by means of a lowering ofthe pitch of the blades the speed increase being co-ordinated in timewith the inr crease of output, and in this way excess thermal stressingis avoided. This increase in speed raises the speed of the superchargingplant, so that the supercharging pressure is also raised. The fuelquantity to be injected can now also be augmented, :and the torque ofthe propelling engine rapidly increases and accelerates the shipcorrespondingly. In view of the rise in the supercharging pressure, thespeed of the engine could now be further increased. If this isnotdesired, however, the pitchA of the propeller blades can, correspondingvto the increase in pressure, be entirely or approximately returned tothe value prevailing before the change in the speed of the ship. y j

lThe device shown in Fig. 3 works as follows:

The kadjusting member 2l is brought, for a given speed of travel of theship, 'from the zero position 0 into, for instance, the position I. Ifnow the speed of travel is to be increased, then the lever 26 isVturned, for instance, from I to II and by means of the rod'28 disp-lacesthe hinge 29 of the lever 3l? into'thel position 29a. The lever 33 turnsabout the fulcrum 3|, which is rigidly connected to the piston 32 in thecylinder 33, sot-hat the hinge 311' comes into the position-34a. r

To the hinge 34 are connected the bell-cranks 35 (Fig. 4),' whichdisplace the rail 36 with the slot 3l transversely. On the rail 36 is aslide pi ece38 with twoV pinsj39, which engage both the 1ers, the end 5sof the rod 51 carrieswnhn y the slot 56, and turns the lever- 54, sothat the with the adjusting rod I and is adjusted inlaccordance with theposition of the piston I4`or the blades 5.

Through the displacement of the hinge 34 into the-position 34a, theslide piece 38 is moved by means of the rail 36 into the position 38a,Fig. 5, and the pins 39 vmove downwards in the slots 40 and 4|, Vso thatthe return lever 43, turning about the hinge on the collar 48, arrivesin vthe position 43a. The control member I1 then moves to the left andconnects the space 4'4 with the supply 46. The piston I4 moves into theposition I 4a and lowers the pitch of the blade 5 which comes into theposition 5a (Fig- 3). Meanwhile the control member I1 is returned by thelever 43 into the closing position, as the lever 43 comes into theposition 43h, Fig. 5.

rIhe internal combustion engine-I can now increase its speed without anychange of the fuel quantity or of the torque, since with the lower pitchthe torque absorbed by the propeller 4 is smaller. The speed of thesupercharging set i, I8 rises, asthe overtaking coupling 2|, at theincreased speed -of the engine I, provides av supplementary drive forthe Vturbine 1 and with it the compressor I8. Now the pressure in thesupercharging pipe I2 and 'in the cylinder 33 rises.

On the one hand, as soon as the supercharging pressure rises, the fuelquantity is increased, for the piston 32 is coupled through vthe rodt tothe casing 5I of the elastic member 5I-53, the spring plate 52 of whichis connected through the lever 54 with the member 5'5 of the fuel pumps26, which member adjusts the quantity of fuel to be .injected into thecylinders of the engine I. The piston 32, which is more highly loaded,moves lto the right in opposition to the pressure of the spring 6I, sothat the casing 5I comes into the position 5I-a and the adjusting member55 moves to the left.

On the other hand, the piston 32 -now displaces the fulcrum 3|, and withit the hinge 34, to the right. Therefore the slide piece. 38 comes fromthe position 38a back to its original position 38 and turns the returnlever 43 into the posi-tion 43C (Fig. 5), which lever moves the controlmember I1 to the right, and thus the space 45 is connected to the supplypipe 46 and the space 44 to the drain pipe 41. The piston I4 returnsfrom the position I4a to the position I4 and turns the blade 5 from theposition 5a (Fig. 3) into the original position 5. the member l1 isbrought into the closing position. sition 43, Fig. 5. l n

For decreasing the speed of travel, it is sumcient to decrease the fuelquantity alone without adjusting the blades 5. The elastic system 5I to53 serves for this purpose. If the lever 21 is moved from the positionII towards the position 0, the cylinder 5I remains in'its position 5Iacorresponding to the position II of the lever 21. The spring plate 52,on the other hand, moves to the left, so that the spring 53 iscompressed. The lever 54 is connected to the lever 21 bythe slot V156and the rod 51. When the lever 21 is moved to adjusting member 55 movesto the right so as to. decrease the fuel quantity. When, however, thellever 21 is moved to the right, the end 58 of the rod 51moves freely inthe slot 56, so that the fuel filling is only changed in accordance withthe increase of the supercharging pressure.

In order to enable the` variable pitchl propeller 4 to be adjustedfromrunning ahead to running astern or to some xed intermediate pitch forcontinuous running, the rod 59 is adjusted by hand or by an adjustingmember not shown in the drawing. The lever 60 displaces the rod 42 withthe slot 40 and thus the slide piece 38 with Athe pins 33, which lareguided in the slot 31 and vcarry with them the return lever 43-and thecontrol member I1.

In Fig. 6 the overtaking coupling ZI is shown. The inner part 22 isconnected to the crankshaft of the engine I and turns in the directionof the arrow 23. The outer part 24-is connected tothe f reduction gear25. If the temperature or the pressure of the exhaustgases, or both, arelow, j

then the speed of turbine -1 falls. If Athe speed falls below the valuewhich corresponds to the Aspeed-ofthe crankshaft and the transmissionchange in it, particularly at part load. A rightly adjusted,non-supercharged internal combustion l engine works also at part loadswithout giving Through the return motion v The return lever arrives inthe original potrouble, because the combustion air can be drawn in fromthe surrounding atmosphere in the same condition and in an unchangedquantity at all speeds of rotation and whether the engine is working atpart load, full load or overload. For this reason the state of thecompressed charging air in the combustion space undergoes no changeworthy of mention when the load changes, and the ignition lag is thesame at all part loads and overloads. In supercharged internalcombustion engines the conditions are different, since as a result ofthe lower speed of the compressor at" part load the combustion `air isprecompressed to a considerably less extent and the compression pressurein the combustion space of the working cylinder is therefore greatlydiminished. The

temperature of the combustion air also falls with shape of the ignitionchamber, the temperatureV of the fuel and other similar features, are ofquite minor signiiicance and .exert scarcely any infiuence on theignition lag.

If a supercharged Yinterna-l combustion engine intended for marinepropulsion is run at part load for the purpose of slowing -orjturningthe vessel, then its speed of rotation is decreased. The decrease`ofspeed is .accompanied by `a decrease `in thel pressure andtemperature of the combustion air inthe combustion space. The'result -isthat the ignition lag increases to several times the -length of thenormal ignition lag.

The fuel which has collected in the combustio space during the time theignition is delayed, will all burst into flame together when ignitionoccurs. When the ignition lag is very considerable,

' an unusually large quantity of fuel will have colvlected and will besuddenly fired. Such ignitions have the character of detonations andcause l a steep rise of pressure and thereby knocking vthe internalcombustion cylinder must also be lkept low, there 'is a danger thatcylinders may misi-ire altogether at low speeds of the engine.

V-Low atmospheric temperatures, fuels which do `not ignite easily andother accompanying circumstances will Afurther increase this danger.lThe running of the engine will then be impaired to such a degree thatnot only is the output decreased out of all proportion but in somecircumstances it may prove impossible to keep the engine working at all.It then either runs with some cylinders misring or stops altogether. Forthe same reason the Starting-up of supercharged engines is rendered moredifficult, a fact which may seriously endanger the vessel duringmanuvres.

The difficulties encountered in plants with supercharged internalcombustion engines, as described above, are overcome by the presentinvention in the following manner: the device for adjusting thepropeller blades and the control or governing device of the internalcombustion engine are coupled to each other by an automatic device insuch a way that, when the vessels speed isdecreased,V the speed of theinternal combustion engine is so adjusted by the setting of thepropeller blades that the pressure of the supercharging air cannot fallbelow 60% of the pressure above the atmospheric pressure yat fullload.

When the method proposed in the invention is used, the absolutetemperature of the com- VVbustion air does not fall below 85% of thatatfull power. In this way the ignition lag at decreased speed of thevessel and even at complete stoppage can be kept at least below threetimes the length of the ignition lag at normal power.

YWithin this range the running of the internal charged enginerplantswith a supercharging pressure of about 2 atm. abs. The size of theinternal combustion engine, the form of its ignition space, the fuelused and other considerations are here of...only very slight influence..Y

' The full-line curve p (Fig. 7) shows the ignition lag for asupercharged internal combustion engine driving a non-adjustablepropeller. The `speed'of rotationhere changes in accordance with thewell-known parabolic propeller law. At about half power the ignitionlagof such an engine plant has already increased to three times thenormalfigure. Y In accordance with the falling supercharging` airtemperatures which acrcompany the speed decrease, the ignition lagincreases much fasterat powers below 1/2 the full power. It reachesVfive times the normalvalue andveven higher figures, Yin which case theig-` nition of the fuel takes place very late and in the form of adetonation accompanied by knocking, or it may even ybe doubtful if itwill takeV place at all. A propelling plant equipped with highlysupercharged internal combustion engines and non-adjustable propellerscan scarcely7 be kept runningatoutputs less than 1/4 of the full power.`

Curve s, theA chaindottedline, shows the con-V Y ditions when the enginedrives an adjustable propeller the bladesof which are so set that thespeed of the engine remains at all outputs the same as at full power. Aslight increase in the ignition lag occurs vhere too, but lies withinlimits in which the reliable running of the supercharged internalkcombustion engine is assured and there is no danger from, violentignition. rIhe engine vcan be started up at speeds which ensureimmediate ignition.

Curve t, the broken line shows the behaviour of the ignition lag whenthe adjustable propeller is set so that it is rotated at only about 80%.of the normal speed. In accordance with the decreased speed, thisbroken curve t lies above the chain-dotted curve s., but almost thewhole of it lies below three times the ignition lag of a normal engineat full load. Even at this lower speed, the ignition lag falls in aregion where the engine can be relied on to start up satisfactorily. Y

The internalY combustion engine I in Fig. 8 drives, through toothed gear65, a propeller the blades 5 of ywhich can be turned about a radial axisby means of devices shown in Fig. 3 or by hand. v

The two-stroke internal combustion engine I, Fig. 8, is provided with Vasupercharging plant which comprises the exhaust-gas turbine 1, theblower I8 driven by this and the reciprocating compressor 2 driven fromthe crankshaft of the engine I. The exhaust-gas pipe 8 conducts theexhaust gases from the engine I to the turbine ll, from which theyescape through the exhaust pipe 9. The blower IIS, which may be designedas a centrifugal, radial 'or axial blower or as a combination of thesetypes, and which may have one or more stages, forms the first stageofthe supercharging plant and delivers the air through the pipe 66 tothe compressor 2, which'compresses it further and delivers it to thecombustion cylinders' through the pipe I2, which may be designed asasupercharging air receiver.

The device for adjusting the propeller blades isoperated with the laidof rod I5. and lever 68. At the. central position 0 of the lever 68 asshown in the'drawing, the rblades 5 are set perpendicular to the axis'of rotation of the propeller 4, so that when the propeller 4 rotatesthey do not exert any force either in the form of Va forward or abackward drive. When the lever 68 is `moved overin the direction of thearrow V, the propeller blades are set so that, when the crankshaftfoftheinternal comb-,ustionengine turns in the direction ofthefarrow 69,the vessel moresaaheadf .Wlieniheleref 6 8 regimes in the direction ofthe arrow R, the vessel pelled astern.

The fuel pump lll is adjusted by means of rod 7|. An adjustment in thedirection of-'the double-headed arrow 72 increases the fuel feed, whilean adjustment in the direction decreases the quantity of fuel.

The device for adjusting the propeller blades, consisting of rod i andlever 63, and the control" or governing device of the internalcombustion engine of which'rod 'II forms part, are coupled to each otherby an automatically acting device in such a way that, when the speed ofthe vessel is decreased by setting the propeller blades, the speed ofthe internal combustion engine can be adjusted so that the pressure ofthe supercharging air in pipe 55 cannot fall below 60% of the pressureabove atmosphere at full power.

Lever 68 carries upon its axis of rotation 13 a cam 'M upon which theroller I5 of a lever 11, mounted on the l-lxed pin 116, can move. Thecrankpin 78 is rigidlyy connected to lever l1. It engages not only theslot 'I9 of a rod 3B, butv also forms the fulcrum of a double-armedlever/8|. This double-armed lever engages on' the one hand with thesleeve 82 of the centrifugal governor 83 and on the other hand with thepin 8f! in the slot 85 of a rod B. Both the rod 8) and the rod 86 aremounted upon a pin 8'! carried on the lever 89, which swings aboutthe'xed pin 88. The rod II of the fuel pump governing device isalsolinked to the pin 81.

A further device limits the angle of'motion of lever 68. In cylinder BIJare placed one springloaded piston SI, which is' loaded on the inside isproby the supercharging pressure in pipe I2 acting through pipe 92.The'mouth of the stopping fork 94, which narrows towards the inside,limits the adjustment of the lever 68 the more, the nearer the fork e4is moved towards the Ylever y68 by the spring 93, when the superchargingpressure in the pipe I2 decreases.

When lever 68 is in the stop position 0, the fuel quantity of the fuelpump is limited by the cam 14 acting through rod 80 in such a way thatthe internal combustion engine still runs at a speed at which thesupercharging compressor I8 produces in'pipe I2 a delivery pressurewhich, even when the vessel travelling at decreased speed or is at astandstill, amounts to at least 60% of the pressure above atmosphere atfull speed of the vessel or at full power of the internal combustionengine I. If for any unforeseen reason the speed of the internalcombustion engine I should become inadmissibly high, then pin 84 wouldpress upon the end of slot 85 ofv rod 86, and would thus furtherdecrease the quantity of fuel. At the same time the contact surface inslot 19, of rod BIJ would move away from pin 18.

When the vessel is to move ahead, lever 6 8 is moved over in thedirection of arrow V. In this way the blades 5 of propeller 4 are swunginto their ahead position. At the Sametime the cam 'I4 moves lever 'Ilin such a way that the pin 18 is displaced in the direction of the arrow95. in the direction of thev double-headed arrow 'l2 in such a way thatrod 3G remains with the inside of its slot 'I9 pressing upon pin 18. Rod'H is thus also adjusted in the direction of arrow "l2, so that theinternal combustion engine l receives an increased quantity of injectedfuel. The stopping fork 94 limits the motion of the lever in such a waythatthe propeller llcannot oppose too high a moment to the internal com-The lever 89 is then displacedby spring 9B bustion engine I. The form ofthe cam 'I4 and the amount which the mouth of the fork .94 nar-- rowstowards the inside are so chosen that, when the propeller blades 5 areadjusted, in accordance with the increased turning moment so much morefuel is injected into the working cylinders that the speed of theinternal combustion-engine I remains'high enough to keep the pressure ofthe supercharging air above the gure of of the pressure above atmosphereat full power.

If the vessel is to be adjusted for motion astern,

the lever is moved over from thestop positionVV 0 in the direction ofarrow R. On account of' the nearly symmetrical form of the cam 14, the

same adjustment of the coupling device and of the device for governingthe internal combustion engine is obtained as for motion ahead, whilethe blades 5 of propeller 4 are set in the opposite direction. With theinternal combustion engine I 4 continuing to rotate in the samedirection, as indicated by arrowy e9, the vessel is now driven astern.For motion astern also, the form of the cam 'l4` andthe adjustment ofstopping fork SM l are chosen so that the speed of the internalcombustion engine cannot fall beyond the point at" which at least 60% ofthe full load pressure is maintained-in pipe I 2. y

In order that not only the mechanical but also a thermal overstressingof the engine l may be avoided, the linkage operated bythe lever 21 inFig. 3 may be used for the fuel regulation by the` cam T4 in place ofthe lever l1 with its attached The lever 21 would then be providedYlinkage. with a roller l5v (Fig. 8) working with the cam 14, this rollerreplacing the handle. this kind, the lever 68 (Fig. 8) then actuates therod 23 (Fig. 3). A

Further, the turbo set l, Ig in Fig. 8 may also be driven by means oftransmission gearing a, Fig. 9, from the gear 65, an intermediate overataking couplingv 2! being provided, as in Fig. 6,

so that whenthe speed of the turbinel' is too low, the overtakingcoupling 2| comes into action In this case the reciprocating compressor2 draws air from atmosphere through the suction j valves situated in asuction chamber. The compressedrair passes from the pressure chamber,into which the delivery valves open, through the air pipe I2 and intothe cylinders of they engine I. v Y

The engine I, Fig. l0, is connected by means of the'gear 65 with thepropeller shaft 3 and the propeller ll with its adjustable blades 5. Thesupercharging plant takes the form of the turbine l andthe blower I8driven by it, an electric motor I9 which is co-nnected up to the vesselsy electric system working on the same shaft.

The exhaust-gas pipe 8 leads to the turbine 1, from which the exhaustgases escape through the pipe 9. The blower I 8 is connected to theengine I through the pipe I2. The motor I9 is sodesigned that it can, inaccordance with the increasing speed of the turbo set 1, I8, follow thechange of speed when the load on the internal In a design of` controlmedium supplied and led off through pipesv 99 and |00 is controlled,according Vto the position of the rotary valve IOI, either by the valve|02 or by the valve |03. The two latter valves are linked to thereturn-motion lever |09 at the points |04 and |05. Further, thereturnmotion lever is connected by means of a link at the point |01 tothe rod |08, which in its turn is linked to the adjusting lever |09. .y

The governing device 1| of the internal com'- bustion engine Y| isconnected to lever I|2 by way of the bell-crank lever I I and the rod III. The lever |09 is pressed against the bearing surface I|3 of lever ||2by means of the spring H4.

ByY means of a pawl the lever H2 can be fixed at any position desiredalongA the notched segment II6.

Although the The position shown in Fig. lO'is` with the vessel atastandstill and the internal combustion engineV running in readiness formotion ahead. The reversing lever III connected to the rotary valveV|`0| is here in the position V and the two levers |09 and I I 2 are inthe position 0. In this position pipes 99 and |00 are connected by wayof the rotary valve I0| to the casing of valve |02. The fulcrum |01 oflever |06 is placed by lever |09 in a position at which theV piston ofthe servomotor is at its middle position and the propeller blades areperpendicular to the axis of rotation'oi the propeller, so'that neithervan aheadinor` an astern drive comes into eiect. The internal combustionengine then runs at a speed which is high enough to ensure asupercharging pressure which is' at least 60% of the pressure above theatmosphere at full power.

If the vessel is to be driven ahead, lever ||2 is first moved over toposition I0. The internaly combustion engine now receives an increasedquantity of fuel, which is again so limited by the governor 83 Athat noinadmissible speed of rotation is reached.Y Thereupon lever |99 can bereleased at point II8. The spring presses it against the stop on leverIIZ. Thus 91 in the direction of the arrow V. The lever |06 also movesin the same direction until the valve |02 is again returned to itsmiddle position, where no further displacement of the piston 91 and thusof the adjusting device I5 takes place. Each position ofllever |09brings about a certain position of the adjusting device I5 for thepropeller blades 5.

If the vessel is to be driven astern, the lever ||1`is moved over to theposition R. In this way the pipes 99 and |00 are connected with thecasing of valve |93. If a certain speed for the vessel is now set bymeans of the fuel lever ||2 and the lever |09, the valve |03 is adjustedso that pressure medium can pass out of the supply pipe |20 throughslide valve |0| into pipe |00. This displaces the piston 91 and theadjusting device I5 in the direction of the arrow The `accompanyingadjustment of the lever |06 thereupon presses the valve |03 back intoits middle position, where vno further control medium can be supplied tothe Vpiston 91.

The transmission ratios of the levers |06, |09 and I|2 are so chosenthat, by the adjustment of the propeller blades, at every part load ofthe internal .combustion engine a speed is ensured at which, thesupercharging pressure amounts to atleast 60% of the superchargingpressure above the atmosphere at full power, so that the ignition lagscannot become more than three times the figure at normal load.

To the lever I I2 is further connected a regulating device forinfluencing the speed of the auxiliary direct-current motor I9. Thisregulating device comprises the yoke |25, which is connected through thespring system |26, |21 and the piston rod |28 to the piston |30 of a'xedcataract |3I. On the yoke |25 is a contact spring |32, which liesagainst the contact piece |33 and is provided in the middle with aninsulating piece |34.

When'the lever |I2 is adjusted, either the spring |26 alone or thespring |21 alone is compressed. The contact piece |33 leaves theinsulating piece'I34 and makes contact with the contact spring |32,whereupon the levers |31, |38 are moved through a switching system |35,

|36 and a displacement 0f the brushes of thev motor I9 is thus effected,as aresult of which the speed of this motor is increased. The piston |30with the bore |29 moves in the same direction as the yoke I 25 wasmoved, so that after some time the contact piece |33 again lies againstthe'insulating piece |34, the current is Ainterlrupted and the lever |31and |38 and thus the brushes of the motor I9 again take up theiroriginal position. In the meantime the engine I has also reached the newload and the speed of the turbine 1 and the supercharging pressure inthe pipe I2 is adapted to this new load.

The same device |25- |38 may be connected to the rod 28, Fig. 3, wheninstead of the Vgear 20 a direct current motor I9 is provided.

Fig. 11 shows a variation in the arrangement of the compressors in Fig.8. The-reciprocating compressor 2 is working as primary compressor whenthe valve |40 is closed. When the'overflow valve |40 is opened, thecompressor I8 is cut out. In another variation inFig. 12 the exhaustgases of the engine I drive a set consisting of the exhaust-gas turbine1 and the compressor I8. The compressor I9 and a second separatelydriven compressor |4I,V which works in parallel with it, deliver to thesupercharging pipe I2. The compressor |4I a Yreciprocating or any typeof rotary compressor, is driven by means of an auxiliary power unit |42,for instance a steam turbine, an electric motor or an auxiliary internalcombustion engine. The internal combustion engine may be of any type;thus it may have a single row of cylinders or several rows, or may be anopposed-piston engine. Moreover, instead of one exhaust-gas turbineV anda compressor driven by it, several sets may be provided, which may, ifrequired, be connected to separate cylinders and have any desiredswitching system.

I claim: Y

1. In a power plant for ship propulsion, the

combination of a two-cycle internal combustion Y engine having fuelsupply means, a gas turbine connected with the exhaust manifold of saidenpower trom said gas turbine and connected with arsenaal)` said enginefor combustion air supply thereto,v

the relative operating characteristics of said engine, turbine andcompressor being such that said compressor draws a volume of airamounting to more than twice and delivers it in compressed state to saidengine at a volume amounting to less than twice its swept volume, at onerevolution of said engine and when it operates at full load, controlmeans connected with said fuel supply means for controlling the fuelsupply to said engine, a variable pitch propeller connected to anddriven by said engine and having a pitch changing mechanism, manuallyoperable means permanently connected with and positioning said pitchchanging mechanism, a link connected with said manually operable meansand having a pin at its free end, connecting means connected with saidfuel control means and with said pitch changing mechanism and comprisinga terminal slot receiving said pin and affording free movement of saidmanually operable means without aiecting said fuel supplymeans atpredetermined operating conditions of said connecting means, and meansresponsive to the pressure of the air delivered by said compressor tosaid engine and interposed in said connecting means and adapted tooverrule the operation of said pitch changing means by said manuallyoperable means at all times.

2. In a power plant for ship propulsion, the combination of a two-cycleinternal combustion engine, a gas turbine connected to and operated byexhaust gas from said engine, an air compressor connected to and drivenby said turbine and connected with said engine for supplying combustionair thereto, the relative operating characteristics of said engine,turbine, and compressor being such that said compresso-r draws a volumeof air amounting to more than twice and delivers it in compressed stateto said engine at a volume amounting to less than twice its sweptvolume, at one revolution of said engine and when it operates at fullload, an electric motor connected with said compressor for supplyingauxiliary driving power, a variable pitch propeller connected to anddriven by said engine, pitch changing means connected with saidpropeller, and motor speed control means connected with said moto-r andwith said pitch changing means for correlating the speed of said motorand compressor and the position of said pitch changing means.

3. In a power control system for a marine power plant comprising avariable pitch propeller, an internal combustion engine driving saidpropeller and having fuel supply means, and an air compressor receivingits driving power from said combustion yengine and delivering compressedcombustion air to said engine at a pressure which is coordinated withthe speed thereof: a pitch changing mechanism, a power output controlmechanism connected with said fuel supply means, actuating means comm'onto both said mechanisms and comprising a one-way effective connectingmeans operative over the whole range of movement of said actuating meansand adapted to connect said fuel supply control mechanism and said pitchchanging mechanism upon movement of said actuating means in thedirection eiecting a decrease of power output of the plant andsuspending connection of said fuel supply control mechanism and saidpitch changing mechanism upon movement of said actuating means in theopposite direction.

4. In a power control system for a marine power plant Ycomprising avariable` pitch propeller, an

internal combustion engine drivingsaid propeller and having fuel supplymeans, and an air compressor receiving its driving power fromsaid'combustion engine and delivering compressed-.combustion air to saidengine at a pressure which is coordinated with the speed thereof: apitch changing mechanism, a power output. control mechanism connectedwith said fuel supply means, an actuating member common to both saidmechanisms and permanently connected with said pitch changing mechanism,a one-way effective connecting means connecting said fuel supply controlmechanism and said actuating member upon movement of the latter in adirection effecting a decrease of the power output of the plant andsuspending connection of said fuel supply control mechanism and saidactuating member upon movement of the latter in the opposite direction,and means connecting said pitch changing mechanism and saidfuel supplycontrol mechanism for making the latter dependent on the position of theformer.

5..In a power control system for a marine power plant comprising avariable pitch propeller,

an internal combustion engine driving said propeller and having fuelsupply means, andan air compressor receiving its driving power from saidVcombustion engine and delivering compressed combustion air to saidengine at a pressure which is coordinated with the speed thereof: apitch changing mechanism, a power output control mechanism connectedwith said fuel supply means, an actuating member common to both saidmechanisms and permanently connected with said pitch changing mechanism,a one-way effective connecting means connecting said fuel supply controlmechanism and said actuating member upon movement of the latter in adirection effecting a decrease of the power output of the plant andsuspending connection of said fuel supply control mechanism and saidactuating member upon movement of the latter in the opposite direction,and means responsive to the combuston ai;1 pressure and permanentlyconnected with and controlling the operation of both said mechanisms atall times.

6. In a power'control mechanism as set forth in claim 5, meansconnecting said pitch changing mechanism and said fuel supply controlmechanism and having said combustion air pressure responsive meansinterposed therein.

7. In a power control system for a marine power plant comp-rising avariable pitch propeller, an internal combustion engine driving saidpropeller and having fuel supply means, and an air compressor receivingits driving power from said combustion engine and delivering compressedcombustion air to said engine: a kvariable speed motor connected withsaid compressor for supplying supplemental driving power thereto andhaving speed changing means, a pitch changing mechanism, a power outputcontrol mechanism connected with said fuel supply means, actuating meanscommon to both said mechanisms and comprising a one-way effectiveconnecting means connecting said fuel supply control mechanism and saidpitch changing mechanism upon movement of said actuating means in thedirection effecting a decrease of power output of the plant andsuspending connection of said fuel supply control mechanism and saidpitch changing mechanism upon movement of said actuating means in theopposite direction, and connecting means interconnecting said actuatingmeans and said speed changing means for changing. the speed of saidmotor upon actuation of said actuating means.

8. In a power control system as defined in claim 7, clutch meansinterposed in said connecting means and comprising yielding clutchengaging means for connecting said actuating means and saidspeedchanging means upon actuation of said actuating means and comprisingresilient disengaging means counteracting said engaging means uponcessation of actuation of said actuating means.

FRITZ ROESCH.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date Re. 15,888 McCauley Aug. 5, 19242,115,485 Dodson Apr. 26, 1938 2,164,545 Rogers July 4, 1939 2,217,364Halford et al Oct. 8, 1940 2,231,292 Neugebauer Feb. 11, 1941 2,280,835Lysholm Apr. 28, 1942 2,306,953 Jung Dec. 29, 1942 2,321,025 HammondJune 8, 1943 2,336,844 Buck Dec. 14, 1943 16 Number Name Date 2,342,410Lieberherr Feb. 24, 1944 2,384,353 Stieglitz Sept. 4, 1945 2,389,003Schorn Nov. 13, 1945 2,396,618 Stieglitz et al Mar. 12, 1946 2,402,885Gilllan et a1 June 25, 1946 2,443,717 Birman June 22, 1948 FOREIGNPATENTS Number Country Date 181,043 Switzerland Nov. 30, 1935 206,845Great Britain Feb. 21, 1924 215,808 Switzerland July 15, 1941 399,520Great Britain Oct. 6, 1933 435,928 Germany Aug. 19, 1923 436,492 GreatBritain Oct. 11, 1935 513,971 Great Britain Oct. 26, 1939 540,774 GreatBritain Oct. 29, 1941 638,367 Germany Oct. 29, 1936 852,019

France Oct. 16, 1939 OTHER REFERENCES Supercharging Two-Stroke Engines,from the Power and Works Engineer, August 1942 (pages 211,212, 213 and218).

The Supercharging of Two-Stroke Diesel Engines, from the SulzerTechnical Review, December 31, 1941 (pages 1-21 inclusive), published bySulzer Bros., Ltd.

